1. Field of the Invention
This invention generally relates to a non-impact type printer such as an ink-jet printer and in particular to a printer head for use in an ink-jet printing system.
2. Background of the Invention
In an ink-jet printing system, several printer heads have heretofore been used. For example, FIGS. 1(a) and (b) show the multi-nozzle on-demand type printer head in which a plurality of vibrators 1 to which an image signal is applied are provided for respective pumping chambers 2, which receive ink from an ink reservoir and supply the ink to the corresponding nozzles 3 through flow passages 4 in response to an image signal applied to the vibrators 1. In such a structure, ink droplets are ejected from those nozzles 3 whose corresponding vibrators 1 have received on-signals and ink droplets are not ejected from those nozzles 3 whose corresponding vibrators 1 have not received on-signals. However, since provision of the vibrators 1 and pumping chambers 2 requires a substantial space, the head tends to be bulky and there has been difficulty in arranging the nozzles 3 at high density. It is true that a high density nozzle array may be obtained by providing a structure as shown in FIG. 1a; however, it should be noted that the flow passages 4 are different in shape and length among those in the top or bottom half in the case of a symmetric arrangement, so that the overall fluid-dynamic resistance differs from one flow passage to another thereby hindering to obtain uniform ink droplets from all of the nozzles.
On the other hand, FIG. 2 shows the multi-nozzle deflection type printer head which comprises a vibrator 10, a vibrating plate 11, an ink chamber 12, a nozzle plate 13, charging electrodes 14, and deflection electrodes 15. In this case, ink is ejected out of the nozzles formed in the nozzle plate 13 to form ink droplets, which are then charged by the charging electrodes and deflected by the deflecting electrodes 15. In such a structure, however, since the charging and deflection electrodes 14 and 15 must be provided in front of the corresponding nozzles formed in the plate 13, it is complicated in structure and thus difficult to manufacture.